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A landmark study published in 1995 reported that routine treatment of bacterial STDs reduced the incidence of HIV. However, a subsequent large, community-based, randomized trial in Uganda failed to demonstrate that treatment of bacterial STDs reduces HIV incidence. The stage of the HIV epidemic in the community, the presence of viral vs bacterial STDs, and the effectiveness of the treatments all likely play a role in the heterogeneous results in these studies.
Several studies have focused on whether treatment of herpes simplex virus (HSV) infection could reduce acquisition and/or transmission of HIV, an idea based on the multiple studies documenting the increased risk of HIV infection among persons infected with HSV-2. However, although studies have shown that treating HSV-2 does reduce HIV/HSV-2–coinfected patients’ HIV-1 RNA level,[47-49] 2 placebo-controlled trials of acyclovir in HIV-uninfected people who were HSV-2–seropositive failed to show any reduction in HIV acquisition among those who received antiviral therapy vs controls.[50,51] The potential of HSV-2 treatment to reduce HIV infectivity has been evaluated in a study of 3408 African women and men coinfected with HSV-2 and HIV. Although daily acyclovir treatment reduced the composite endpoint risk of the first CD4+ cell decline to 200 cells/mm3, ART initiation, or nontrauma-related death by 16% and substantially reduced the rate of HSV-2–positive genital ulcer disease, there was no overall effect of acyclovir on transmission of HIV to uninfected partners, even though HSV virologic suppression modestly reduced HIV-1 RNA.
Despite numerous studies suggesting that HSV-2 infection is an important risk factor for acquiring HIV, studies to date have failed to demonstrate an impact of HSV-2 suppressive therapy on either HIV susceptibility or infectiousness. It is possible that acyclovir therapy incompletely suppresses local inflammatory changes associated with HSV-2 infection. Because the studies had high levels of self-reported adherence to drug therapy and because lower levels of genital ulcer disease were seen following acyclovir therapy, the negative results of these trials have not been attributed to low levels of drug adherence.
Taken together, this series of studies suggests that prevention of HIV infection through suppression or control of cofactors, such as effectively treating an active STD, is unlikely to have a sufficient impact to significantly decrease HIV transmission.